This invention relates to electrographic apparatus, that is apparatus for producing electrical signals representing data as to the position of a point on a surface. In one application, the invention is concerned with obtaining data related to the movement of a point, such as a pen or stylus, over a sheet which data can be coded for computer processing for eventual reproduction or can be used for transmission to a distance for facsimile reproduction. By this means, hand-written documents or drawings can be reproduced by computer processing or by simultaneous reproduction.